Hi
i have a 1999 Dodge Ram 2500 5.9l cummins I ran into the “no bus” code 10/31/21 all gages quit working on cluster, fuel light came on, engine light…. And my truck was not shifting. So I replaced the computer last night (11/19) it was fine until I actually started the truck and then bam the no bus came back on, no change. I am really confused and just hoping I did not waste all of that money. We are going to check all connections tonight, just was wondering if there was any other suggestions to try? I am stumped.

 

Unfortunately quite a few people had similar experiences. The issue is that "no bus" in the cluster means it detects no activity on the bus but it's not a definite indication of a dead PCM.. It *could* be the PCM but it could also be defective wiring or another misbehaving module like e.g. the ABS module. A good primer on the CCD bus is here: CCD Bus
The bus uses 5V to create the signal on the bus and 5V is also used for sensors. There have been reports where shorted sensor supply wiring created all sorts of havoc (I have not seen that first hand though). Given that the transmission is on the fritz as well I'd be looking along those lines. One test is to disconnect the transmission connector and see if that makes a difference for the cluster (the transmission won't shift automatically when disconnected). If so, there is a wiring issue inside the transmission which is not uncommon.

 

Had a buddy run into similar problem and he found one pin was pulled from back of cluster connector